Thread grinding machine



April 12, 1955 A. H. BAILEY ETAL THREAD GRINDING MACHINE 5 Sheets-Sheet 1 Filed May 3, 1952 INVENTORS ALBERT H. BA/LEY LEsTjE/Q /-T CHAFFEE BY A Tom/5Y5 April 12, 1955 A. H. BAILEY ETAL 2,705,852

THREAD GRINDING MACHINE Filed May 3, 1952 5 Sheets-Sheet 2 INVENTORS ALBERT H. BA/LEY' I LESTER F CHAF/TEE April 12, 1955 A. H. BAILEY ETAL Tl-IREAD GRINDING MACHINE 5 Sheets-Sheet 3 Filed May 3, 1952 5 m m m m ALBEP H. BA/LEY LESTER ECHAFFEE AT OPNEYS April 12, 1955 A. H. BAILEY ETAL 2,705,852 THREAD GRINDING MACHINE Filed May 3. 1952 5 Sheets-Sheet 4 I v INVENTORS L ALBEQT H. BA/LEY LESTER E CHAFFEE ATT IQNEYJ April 12, 1955 A. H. BAILEY ETAL 2,705,852

THREAD GRINDING MACHINE Filed May 3, 1952 5 Sheets-Sheet 5 F/G/OB INVENTORS ALBERT H BA/LEY BYLEJTEP F. CHA FFEE b W We United States Patent THREAD GRINDING MACHINE Albert H. Bailey, Cromwell, and Lester F. Chaifee, Middletown, Conn., assignors to The Whitney Chain Company, Hartford, Conn., a corporation of Connecticut Application May 3, 1952, Serial No. 285,942

20 Claims. (Cl. 51-5) The present invention relates to machine tools and more particularly to an improved thread grinding machine having many advantages from the standpoint of simplicity and efficiency of operation, and accuracy and reliability in use.

An object of the present invention is to provide a thread grinding machine which can be set up for operation on a workpiece and which, after setting up, will be effective to operate on such pieces, preferably semi-automatically, in large volume over long periods of time without loss of accuracy and the resulting production of rejects and without the need for frequent adjusting or resetting.

A further object of the invention is to provide such a machine which is simple and easy to operate and which can be handled with a minimum of instruction and experience, the machine being foolproof in operation and the operator being relieved of the necessity for adjusting and regulating the operation even during long periods of operation.

Another object of the invention is to provide a machine of the character described which is of simple and rugged construction and suitable for semi-automatic operation, which will stand up under continuous or long production runs and which will operate efficiently and efiectively at all times.

A more specific object is to provide a thread grinding machine employing a grinding wheel in which the grinding wheel may be subjected to re-crushing periodically as required to accurately retain the desired form and pitch of the thread, such re-crushing being accomplished in a simple, effective and quick manner and without loss of the accuracy of setting, the result being that the thread grinding of successive parts is accomplished with a wheel of proper form and positioned properly with respect to the workpiece at all times.

Other objects will be in part obvious and in part pointed out more in detail hereinafter.

The invention accordingly consists in the features of construction, combination of elements and arrangement of parts which will be exemplified in the construction set forth and the scope of the application of which will be indicated in the appended claims.

In the drawings:

Fig. 1 is a front view of a complete machine constructed in accordance with the invention;

Fig. 2 is a cross-sectional view taken along the line 2--2 of Fig. l with the machine in thread grinding position;

Fig. 3 is a cross-sectional view taken along the line 33 of Fig. 2;

Fig. 4 is an enlarged cross-sectional view taken along the line 44 of Fig. l with the machine in position for crushing the form on the grinding wheel;

Fig. 5 is a fragmentary cross-sectional view taken along the line 55 of Fig. 4;

Fig. 6 is a fragmentary rear view partially in cross section showing certain of the control mechanism;

Fig. 7 is an enlarged fragmentary front view of the milling cutter assembly;

Fig. 8 is an enlarged plan view of the crusher assembly;

Fig. 9 is a fragmentary cross-sectional view taken along the line 9-9 of Fig. 1;

Fig. 10A is a diagrammatic view showing the machine elements in position for milling the crusher roll by the thread milling cutter;

Fig. 103 is a diagrammatic view showing the machine elements in position for crushing the form on the grinding wheel by the crusher roll;

ice

Fig. is a diagrammatic view showing the position of the machine elements during the thread grinding of a workpiece; and

Figure 11 is an enlarged detail view of the floating mount for the grinding wheel.

Before taking up the elements of the machine shown in the drawings in detail, it may be helpful in the understanding of the invention to point out that the machine comprises four main assemblies, these being a Workholding and -rotating assembly A, a grinding wheel assembly B, a crusher roll assembly C, and a milling cutter assembly D. These assemblies are mounted on the machine for movement relative to each other as required either under direct manual or semi-automatic control to permit large volume grinding of the workpiece over long periods of time without adjustment while retaining the desired accuracy of form and pitch of thread.

Turning to the drawings in detail, there is shown in the front view of the complete machine in Fig. l of the drawings a base 10 having mounted thereon at the lefthand end, as viewed in Fig. l, the work-holding and -rotating assembly A. The work-holding and -rotating assembly A comprises a stationary head 11 provided with a rotatable spindle 12 and conventional means, such as a motor (not shown), for driving the rotatable spindle 12. The projecting end of the spindle 12 is provided with a conventional chuck or collet 15 for holding the work. The chuck or collet 15 may be of any of the standard types such as, for example, the expanding arbor type for engaging the interior of cylindrical workpieces on the exterior of which the threads are to be ground, or may be a manually operated three-jaw chuck, etc. The head 11 may be provided with a manual control lever 14 which is utilized to initiate the operation of the machine after the work-piece is in place.

To the right of the work-holding and -rotating assembly A is a carriage 20 which is mounted on the base for sliding movement toward and away from the Work-holding and -rotating assembly A. As will be apparent from the following description, the movement of the carriage toward the work-holding and -rotating assembly during a thread grinding operation gives the proper lead to the thread. The carriage is preferably advanced in timed relationship with the rotation of the spindle 12 by means of a cam or the like (not shown) driven by the spindle drive motor of assembly A. The carriage 20 is provided with a slotted guideway 21 extending from front to back in. which is received the tongue 22 of a cross slide 23. The cross slide 23 is moved forwardly and rearwardly of the machine by means of a hydraulic cylinder 24 which is mounted on the carriage 20 and which is fastened at its rear end to the bracket 26 fixed to the carriage 20. The cylinder receives a piston and piston rod assembly 25 fastened at its forward end to the cross slide 23.

Mounted on the front of the cross slide 23 is a vertically movable slide 30 on which is mounted the grinding wheel assembly B previously referred to. The mounting of the slide 30 is best shown in Fig. 9 of the drawings, there being a vertical groove 31 in the front face of the main slide 23 and a tongue 32 on the slide 30 engaging in the groove 31. In order to obtain constant crushing pressure, the slide 30 is urged downwardly by a piston 33 which is disposed in a hydraulic cylinder 34 fixed to the main slide 23. The piston rod 35 is connected at its upper end such as by means of adjustable glblls 36 to the flange 37 of the vertically movable slide Mounted in the vertically movable slide 30 is a rotatable spindle 40 to which is fastened, at the lefthand end as viewed in Fig. 1, a conventional grinding wheel 41. The righthand end of the spindle 40 is provided with a pulley 42 which is driven by V-belts 43 extending about a pulley 44 which is driven by a hydraulic motor 45. The hydraulic motor 45 is supplied with fluid under pressure by means of a flexible hose 46 which accommodates movement of the motor with the slides. In the interest of safety, a housing 47 is placed about the exposed moving parts of the grinding wheel assembly.

Slidably mounted for vertical movement at the lefthand face of the cross slide 23, as viewed in Fig. 1 of the drawings, is the milling cutter assembly D previously referred to. As best shown in Figs. 4, 7 and 9, the milling cutter assembly D comprises a vertically movable slide 50 which is provided with a tongue 51 engaging in the recess 52 of the cross slide. The slide 50 has secured thereto a hydraulic motor 53 which by means of worm 54 and worm wheel 55 drives the spindle 56 on which is mounted the thread milling cutter 57. The vertical slide 50 may be adjusted vertically by turning the threaded rod 58 which is threadedly received in the slide 50 at 59 and which is supported against axial movement by a cap 60 disposed in the top of the main slide 30. The upper end of the rod 58 is made polygonal for receiving a suitable turning tool. The slide 50 may be locked against accidental movement by means of a clamp indicated generally at 61 and which is operated by the external handle 62.

Disposed on the carriage 20 between the head 11 and the cross slide 23 is a frame 70 on which is positioned the crusher roll assembly C previously referred to. As best shown in Figs. 2, 3 and 8 of the drawings, the crusher roll assembly C is mounted in a vertically movable slide 71 having a tongue 72 received in the vertical guideway 73 of the frame 70. The slide 71 is held in vertically adjusted position, as best shown in Fig. 4 of the drawings, by a plate 74 secured to the upper end of a threaded post 75 which is received in an adjustable nut 76 to be described more particularly hereinafter. Mounted on the carriage 20 is a hydraulic motor 77 connected by a one-way clutch 78 to the spindle 79 on which is fixed the crusher roll 80.

As best shown in Fig. 1 of the drawings, the grinding wheel 41, the milling cutter 57, and the crusher roll 80 are disposed in the same vertical plane and this relationship is retained at all times because these three rotatable elements are mounted on the carriage 20 on slides which move only in a vertical direction relative to said carriage. The work-holding spindle or arbor 12 is arranged so that when the workpiece is placed thereon and the operator initiates the operation of the machine, the workpiece on which the threads are to be ground will be properly positioned for engagement by the grinding wheel upon forward movement of the cross slide and the proper lead will be obtained by sidewise movement of the carriage 20. As will be apparent, movement of the cross slide 23 forwardly and rearwardly of the machine may be utilized to position the grinding wheel 41 into engagement with the workpiece or with the crusher roll 80 or out of engagement with either of them. Similarly, forward movement of the cross slide 23 may be utilized to bring the milling cutter 57 into operating engagement with the crusher roll 80.

When an operator is setting up the machine for operation the clamp 61 is first released and the slide 50 is then adjusted by turning the threaded rod 58 to position' the milling cutter 57, having the desired form for producing the threads, in alignment (vertically) with the particular workpiece on which the machine is to operate. After this is accomplished, the crusher roll 80 is adjusted vertically so that when it is brought into engagement with the milling cutter 57 it will be properly milled to receive the negative of the profile of the milling cutter 57. The crusher roll, as is well known, is a steel roll of the type which while pressed into the periphery of the rotating grinding wheel will dress the same properly by crushing the periphery of the wheel to the desired shape of profile. The means for adjusting the vertical position of the crusher roll 80 is best shown in Figs. 4 and of the drawings. As previously mentioned, the slide 71 is retained in position by the threaded post 75 extending through the adjustable nut 76. The adjustable nut 76 is fixed to a gear 84 which is rotatably supported on the roller bearing assembly 85, these latter parts being disposed in a cavity 86 formed in the carriage 20. The gear 84 is in mesh with idler gear 87 which in turn meshes with the pinion 88 which is fixed to a vertical shaft 89 having at its upper end a hand wheel 90. The vertical shaft 89 is journaled in a housing 91 mounted on the carriage of the machine. As will be apparent, rotation of the hand Wheel 90 will cause the nut 76 to be rotated, thereby raising or lowering the threaded post 75, which in turn fixes the position of the slide 71.

The grinding wheel 41 is then'adjusted so that when it is brought into engagement with the crusher roll 80 it will receive the desired form and pitch of thread. Vertical adjustment of the grinding wheel 41 is accomplished by vertically adjusting the slide 3 which is accomplished by turning the hand wheel 100. The hand wheel is fixed to the rear end of a shaft 101 which is journaled in cross slide 23 and which has at its forward end a worm 102 which is in mesh with a worm wheel 103 which in turn is fixed to the lower end of a threaded post 104 extending vertically of the machine. The upper end of the threaded post is received in a threaded bushing 105, which slidably extends through a bracket 106 fixed to the vertical slide 30. The bushing is provided with adjustable nuts 107 and 108 at opposite ends thereof for engagement with the upper and lower surfaces of the bracket 106, the nut 107 being detached from the bushing 105 and separately retained in place on the post 104 by means of a setscrew 109 and the nut 108 being integral with said bushing. By proper adjustment of-the nuts 107 and 108 limited free movement of the slide 30 is permitted. As described previously, the slide 30 is biased or urged downwardly under constant fluid pressure by means of piston 33 and hydraulic cylinder 3.4. Therefore, the lower nut 108 will effectively limit the lowermost position of the grinding wheel while the upper nut 107 may be adjusted to permit the floating movement of the grinding wheel when subject to crushing pressure. A clearance providing a free movement of the order of /s inch is generally satisfactory for this purpose. By reason of the floating arrangement of the vertical slide 30 and the constant pressure exerted thereon by the hydraulic cylinder 34, there is provided a distinct advantage in that when the grinding wheel engages the workpiece or the crusher roll 80, it will be applied under a constant predetermined force which is particularly important during crushing to obtain uniform crushing pressure. The floating arrangement for the grinding wheel is accomplished without any loss of accuracy.

With the machine properly set up as described, the machine may then be placed into operation for grinding threads on a series of workpieces. All that the operator has to do to place the machine in operation is to secure a workpiece on the chuck or collect 15 and then start the head 11 in motion by actuating the control lever 14. It' is to be understood that during operation of the machine the grinding wheel is being driven at suitable speed by hydraulic fluid admitted to the fluid motor 45 by hose 46. By suitable means such as a valve control (not shown) fluid under pressure may be admitted to the rear end of the cylinder 24 simultaneously with the operation of the head 11 to advance the cross slide 23 to the forward position at which the grinding wheel 41 engages with the workpiece, this position being illustrated in Fig. 2 of the drawings with the workpiece being shown in dotted lines at 110. The forward motion of the slide 23 is controlled by a connecting rod 111 which is fixed to the slide and which passes through an opening 112 in the bracket 26. The rear end of the connecting rod 111 has a pair of lock nuts 113 which may be adjusted to accurately stop the slide in the grinding position. The movement ofthe main slide is halted when the nuts 113 engage against a gate 114 which normally rests on the rod 112 behind the bracket 26. When the grinding of the workpiece has been completed, the fluid pressure on the hydraulic cylinder 24 may be automatically reversed to move the main slide rearwardly and the rotation of the spindle 12 holding the workpiece is stopped. Rearward movement of the cross slide 23 is halted mechanically by means of a cam or other device (not shown) which closes the passageways to the hydraulic cylinder 24, thus fixing the position of the cross slide.

The machine is then repeatedly operated with additional workpieces until it is found that re-crushing of the grinding wheel 41 is required in order to accurately produce the desired thread on the workpiece. The number of operations prior to re-crushing of the grinding wheel is counted by means of a magnetic counter disposed at the side of the base 10. The magnetic counter 120 is of any commercially available predetermining type which may be set to initiate the operation of an associated mechanism at any predetermined count or number of operations. The magnetic counter 120 is thereupon set to actuate an associated mechanism at a count which is slightly less than the number of operations of the machine which, it has been determined, will result in a need for recrushing of the grinding wheel. The magnetic counter 120 may be connected by any suitable means including relays and valves (not shown) so that when the predetermined count has been reached it will cause fluid under pressure to be admitted to the forward end of the hydraulic cylinder 24 to move the main slide rearwardly sufficiently to engage the grinding wheel with the crusher roll 80. If desired, means (not shown) may be provided to de-accelerate the grinding Wheel by reducing the flow of fluid to motor 45 during crushing, since preferred thread grinding speeds are usually higher than preferred crushing speeds. At the same time, the same means actuated by the counter 120 may be utilized to energize the solenoid 125 (see Fig. 3) which has its armature 26 connected to arm 127 mounted on sleeve 128 disposed about the shaft 101. Turning of the sleeve 128 by solenoid 125 causes the pawl 130 on the end of arm 129 fixed to the sleeve 128 to advance the ratchet wheel 131 a predetermined number of teeth. When the solenoid 125 is de-energized, spring 132 connected to arm 133 returns the sleeve 128 to original position. The ratchet wheel 131, being connected to the shaft 101, causes the threaded post 104 to turn in the threaded bushing 105 thus permitting the vertical slide 30 to be lowered under the pressure of the hydraulic cylinder 34 sufiiciently to take care of the decrease in diameter of the grinding wheel due to the crushing operation. While this figure is not critical, it has been found in actual operation that if the mechanism is adjusted to permit the slide to be lowered .0005 inch during each crushing operation, the wheel will be properly dressed. Since the crusher roll 80 has a fixed vertical position during this operation, it will be appreciated that the relationship of the grinding wheel to the workpiece following crushing will not be disturbed. As a result, when the machine returns to normal operation, the accuracy of the thread grinding of the workpiece will proceed as before without any sacrifice of accuracy.

After the machine has been in operation long enough so that the crusher roll 80 has been utilized a repeated number of times to dress the grinding wheel 41, it becomes necessary to re-mill the crusher roll. The number of operations of the crusher roll permitted before remilling can readily be determined by experimentation. A second magnetic counter 81 of the predetermining type may be connected to the machine to register the number of operations following each milling of the crusher roll 80. When the predetermined number of operations has been counted so that re-milling of the crusher roll 80 is required, the magnetic counter, preferably by energizing a signal light 140, will indicate the same to the operator. When the signal light 140 is lit the operator may then push a control button 141 which energizes the solenoid 142 which, in turn, pivots the gate 114 to non-obstructing position permitting the main slide to advance forwardly a sufiicient distance to bring the milling cutter 57 into engagement with the crusher roll 80, this position being shown diagrammatically in Fig. A of the drawings.

The pivoting of the gate 114 actuates a switch 145 which may be connected to open a valve admitting fluid under pressure to the hydraulic motors 77 and 53. At the same time, for example, by means of a solenoid operated valve (not shown), fiuid under pressure is admitted to the rear end of the hydraulic cylinder 24 which advances the cross slide 23. By reason of pivoting of the gate 114 the slide moves forwardly sufficiently to engage the rotating crusher roll 80 with the milling cutter 57 as previously described.

When the crusher roll 80 is to be re-milled, it is automatically elevated a sufficient distance to allow enough material to be removed to restore the desired form. The raising of the crusher roll 80 is accomplished by raising the slide 71. The mechanism employed is best shown in Fig. 5. This mechanism comprises a solenoid 150 having its armature 151 connected by link 152 to one end of an arm 153 which is pivoted at its midpoint on the shaft 89 and having at its other end a pawl 154 biased into engagement with the periphery of a ratchet wheel 155 which is fixed to the shaft 89. The pawl 154 is biased into engagement with the ratchet wheel 155 by means of spring 156 and after energizing of the solenoid 150, the ratchet mechanism is returned to initial position by return spring 157. At the completion of the re-milling operation, the machine is returned to original position by the hydraulic cylinder 24.

It thus will be seen that there has been provided in accordance with the invention a mechanism whereby a grinding wheel may be set up for operation with a given workpiece and thereafter the grinding wheel may be periodically dressed by means of a crusher roll and the crusher roll in turn may be periodically remil1ed to preserve the proper form and pitch of threads, all without disturbing the relationship between the grinding wheel and the workpiece and therefore without sacrifice of accuracy. As a result the machine may be initially adjusted for operation with a given workpiece and thereafter may be placed in operation continuously over long periods of time for long production runs without failure and without sacrifice of accuracy and efficiency, all without any necessity on the part of the operator for resetting or adjusting the machine. The operation of crushing and re-milling cycles may be semi-automatic in nature and these cycles are extremely simple and convenient to carry out with a minimum of skill and a minimum loss of time. The machine is foolproof in operation and particularly suited for large volume production purposes.

When used in the claims, the statement that the bottoms of the grinding wheel and milling cutter are in alignment with and/or engage the tops of the work piece and crusher roll is intended to mean that the elements referred to come into working engagement and that it is the pitch line of the thread forms on these elements which is actually in line.

As many changes could be made in the above construction and many apparently widely different embodiments of this invention could be made without departing from the scope thereof, it is intended that all matter contained in the above description or shown in the accompanying drawings shall be interpreted as illustrative and not in a limiting sense.

It is also to be understood that the language used in the following claims is intended to cover all of the generic and specific features of the invention herein described, and all statements of the scope of the invention which, as a matter of language, might be said to fall therebetween.

We claim as our invention:

1. In a thread grinding machine, a support, a carriage mounted for travel in opposite directions on said support, a slide mounted on the carriage and movable transversely of the carriage travel, a grinding wheel rotatably mounted on the slide, a milling cutter rotatably mounted on the slide, said grinding wheel and milling cutter being mounted in spaced apart relationship for rotation in radial alinement, work holding means on said support for positioning a workpiece in radial alignment with the grinding wheel when said carriage is in one portion of its travel, a crusher roll rotatably mounted on the carriage for rotation in radial alinement with the grinding wheel and milling cutter, and means for moving the slide to a first position to bring the grinding wheel in contact with the workpiece when said carriage is in said one portion of its travel, to a second position with the grinding wheel in contact with the crusher roll, and to a third position with the milling cutter in contact with the crusher roll.

2. In a thread grinding machine, a support, a carriage mounted for travel in opposite directions on said support, a slide mounted on the carriage and movable transversely of the carriage travel, a grinding wheel rotatably mounted on the slide, a milling cutter rotatably mounted on the slide, said grinding wheel and milling cutter being mounted in spaced apart relationship for rotation in radial alinement, work holding means on said support for positioning a workpiece in radial alinement with the grinding Wheel when said carriage is in one portion of its travel, a crusher roll rotatably mounted on the support for rotation in radial alinement with the grinding wheel and milling cutter, means on said support for reciprocating the slide transversely of said carriage travel, and means for controlling the last named means to repeatedly bring the grinding wheel into contact with workpieces disposed in said work holding means when said carriage is in said one portion of its travel to periodically bring the grinding wheel into contact with the crusher roll, and to periodically bring the crusher roll into contact with the milling cutter.

3. In a thread grinding machine, a support, a carriage mounted for travel in opposite directions on said support, a slide mounted on the carriage for linear movement transversely of the carriage travel, a grinding wheel rotatably mounted on the slide, a milling cutter rotatably mounted on the slide, said grinding wheel and milling cutter being mounted in spaced apart relationship. and having their peripheries substantially tangent to one side of a line parallel to the path of movement of the slide, a crusher roll rotatably mounted on said carriage, work holding means fixedly positioned on said support, said crusher roll and work holding means being in spaced apart relationship and arranged so that the peripheries of said crusher roll and a workpiece held by said work holding means are substantially tangent to the other side of said parallel line, and means on said support for moving the slide to a first position to bring the grinding wheel in contact with the workpiece, to a second position with the grinding wheel in contact with the crusher roll, and to a third position with the milling cutter in contact with the crusher roll.

4. In a thread grinding machine, a support, a carriage mounted for travel in opposite directions on said support, a slide mounted on said carriage for linear movement in a horizontal direction, a grinding wheel rotatably mounted on the slide, a milling cutter rotatably mounted on the slide, said grinding wheel and milling cutter being mounted in spaced apart relationship for rotation in radial alignment and having the lowest points of their peripheries in substantially horizontal-alignment, work holder means on the support for positioning a workpiece in engagement with the bottom of the grinding Wheel, a crusher roll mounted on the carriage at a height for engagement with the bottoms of the grinding wheel and milling cutter, and means on said carriage to reciprocate the slide to selectively engage the grinding wheel with a workpiece or with the crusher roll or to engage the milling cutter with the crusher roll.

5. In a thread grinding machine, a support, a carriage mounted for travel in opposite directions on said support, a slide movably mounted on the carriage, work holding means on the support for rotating a workpiece, a crusher roll rotatably mounted on the carriage, a grinding wheel rotatably mounted on the slide and movable thereby into engagement selectively with the workpiece and crusher roll, a milling cutter rotatably mounted on the slide and movable thereby into engagement with the crusher roll, means on the slide for adjusting the height of the milling cutter so that its bottom is in substantial alignmentwith the top of the workpiece, means on the carriage for maintaining the crusher roll at a height for engagement with the bottom of the milling cutter, and means on the slide for maintaining the grinding wheel at a height for engagement with the top of the crusher roll. I

6. In a thread grinding machine, a support, a carriage mounted for travel in opposite directions on the support, a slide movably mounted on the carriage, work holding means on the support for rotating a workpiece, a crusher roll rotatably mounted on the carriage, a grinding wheel rotatably mounted on the slide and movable thereby into engagement selectively with the tops of the workpiece and cmsher roll, a milling cutter rotatably mounted on the slide and movable thereby into engagement with the top of the crusher roll, said milling cutter being adjustably mounted so that its bottom can be moved in substantial alignment with the top of the workpiece, indexable means on the carriage for raising the crusher roll before a milling operation, and indexable means on the slide for lowering the grinding wheel before a crushing operatlon.

7. In a thread grinding machine, a support, a carriage mounted for travel in opposite directions on said support, a slide mounted on said carriage for movement transversely of the carriage travel, a milling cutter rotatably mounted on the slide, a grinding wheel rotatably mounted on the slide and spaced from the milling cutter for rotation in radial alignment therewith, a crusher roll rotatably mounted on the carriage for rotation in radial alignment with the milling cutter and grinding wheel, said crusher roll being mounted for engagement with the bottoms of the milling cutter and grinding wheel, selectively, depending on the position of the slide, indexable means on the carriage for raising the crusher roll before a milling operation, and indexable means on the slide for lowering the grinding wheel before a crushing operation.

8. In a thread grinding machine, a support, a carriage mounted for travel in opposite directions on the support, a cross slide supported on the carriage and mounted for movement transversely of the carriage travel, a secondary slide mounted on the cross slide for vertical movement toward and away from the carriage, a milling cutter rotatably mounted on the cross slide, a grinding wheel rotatably mounted on the secondary slide for rotation in radial alignment with the milling cutter, a crusher roll rotatably mounted on the carriage for rotation in radial alignment with the milling cutter and grinding wheel, said crusher roll being mounted for cooperation with the grinding wheel when the cross slide is moved in one direction and for cooperation with the milling cutter when the cross slide is moved in the opposite direction, and indexable means on the carriage for varying the elevated positions of the crusher roll and grinding wheel relative to the milling cutter.

\ 9. In a thread grinding machine, a support, a carriage mounted for travel in opposite directions on the support,

a slide supported on the carriage and mounted for movement transversely of the carriage travel, a milling cutter rotatably mounted on the slide, a grinding wheel rotatably mounted on the slide for rotation in radial alignment with the milling cutter, a crusher roll rotatably mounted on the carriage for rotation in radial alignment with the milling cutter and grinding wheel, said crusher roll being mounted for engagement with the grinding wheel when the slide is moved in one direction and for engagement with the milling cutter when the slide is moved in the opposite direction, means on the slide for adjusting the vertical position of the milling cutter, indexable means on the carriage for raising the crusher roll before a milling operation, and indexable means on the slide for lowering the grinding wheel before a crushing operation.

10. In a thread grinding machine, a base, a carriage mounted for travel in opposite directions on the base, a slide mounted on the carriage for movement transversely of the carriage travel, a milling cutter rotatably mounted on the slide, a support on the slide mounted for movement toward and away from the carriage, means biasing the support toward the carriage, a stop on the slide for retaining the support in selected elevated position, a grinding wheel rotatably mounted on the support for rotation in radial alignment with the milling cutter, a crusher roll rotatably mounted on the carriage for rotation in radial alignment with the milling cutter and grinding wheel, said crusher roll being mounted for en gagement with the bottoms of the milling cutter and grinding wheel, selectively, depending on the position of slide, indexable means on the carriage for raising the cruser roll before a milling operation, and indexable means on the slide for lowering the support stop means before a crushing operation.

11. In a thread grinding machine, a base, a carriage mounted for travel in opposite directions on the base, a slide mounted on the carriage for movement transversely of the carriage travel, a milling cutter rotatably mounted on the slide, a grinding wheel rotatably mounted on the slide for rotation in radial alignment with the milling cutter and spaced therefrom, a crusher roll mounted on the carriage for rotation in radial alignment with the milling cutter and grinding wheel, said crusher roll being mounted for engagement with the bottom of the milling cutter when the slide is in a first position and for en gagement with the bottom of the grinding wheel when the slide is in a second position, work holding and rotating means on the base, means for moving the carriage toward and away from the last named means, said grinding wheel being engageable with the top of the workpiece when the slide is in a third position, means for adjusting the vertical position of the milling cutter for alignment of the cutter with the top of the workpiece, indexable means on the carrage for raising the crusher roll before a milling operation, and indexable means on the slide for lowering the grinding wheel before a crushing operation.

12. In a thread grinding machine, a base, a carriage mounted for travel in opposite directions on the base, a cross slide mounted on the carriage for horizontal movement transversely of the carriage travel, a milling cutter rotatably mounted on the cross slide, a secondary slide mounted for vertical movement on the cross slide, a grinding wheel mounted on the secondary slide for rotation in radial alignment with the milling cutter, a crusher roll mounted on the carriage for rotation in radial alignment with the milling cutter and grinding wheel, said crusher roll being mounted for engagement with the bottom of the milling cutter during a milling operation when the cross slide is in a first position and for engagement with the bottom of the grinding wheel during a crushing operation when the cross slide is in a second position, work support means on the base for rotating a workpiece, said grinding u heel being engageable with the top of the workpiece when the cross slide is in a third position, means on the carriage for moving the cross slide to said third position during a thread grinding operation, means on the carriage for intermittently moving the cross slide to said second position to crush the grinding wheel, and means on the carriage for intermittently moving the cross slide to said first position for milling the crusher roll.

13. In a thread grinding machine, a base, a carriage mounted for travel in opposite directions on the base, a cross slide mounted for horizontal movement on the carriage transversely of the carriage travel, a milling cutter rotatably mounted on the cross slide, a secondary slide mounted for vertical movement on the cross slide, a grinding wheel mounted on the secondary slide for rotation in radial alignment with the milling cutter, a crusher roll mounted on the carriage for rotation in radial align ment with the milling cutter and grinding wheel, said crusher roll being mounted for engagement with the bottom of the milling cutter during a milling operation when the cross slide is in a first position and for engagement with the bottom of the grinding wheel during a crushing operation when the cross slide is in a second position, work support means on the base for rotating a workpiece, said grinding wheel being engageable with the top of the workpiece when the cross slide is in a third position, means on said carriage for moving the cross slide to said first, second and third positions, selectively, indexable means on the cross slide for lowering the secondary slide before a crushing operation, and indexable means on the carriage for raising the crusher roll before a milling operation.

14. In a thread grinding machine, a base, a carriage mounted for travel in opposite directions on the base, a cross slide mounted for linear sliding movement on the carriage transverse to the carriage travel, a secondary slide mounted on the cross slide for vertical sliding movement toward and away from the carriage, a grinding wheel rotatably mounted on the secondary slide, power means disposed on the secondary slide for rotating the grinding wheel, fluid pressure actuated means biasing the secondary slide toward the carriage, indexable stop means on the cross slide for limiting downward movement of the secondary slide, means on the base for rotating a workpiece, means for advancing the cross slide to bring the grinding wheel into operation against the top of the workpiece, a crusher roll, indexable means on the carriage for positioning the crusher roll at varying elevations in radial alignment with the grinding wheel, power means for driving the crusher roll during a milling operation, means for moving the cross slide to bring the grinding wheel into cooperation with the top of the crusher roll after a predetermined number of thread grinding operations, said last named means being arranged to index the secondary slide stop means, a milling cutter rotatably mounted on the cross slide for rotation in radial alignment with the grinding wheel and crusher roll, power means on the cross slide for driving the milling cutter, means on the cross slide for adjusting the vertical position of the milling cutter, and means on the carriage for advancing the cross slide to bring the milling cutter into operation against the top of the crusher roll and for indexing the crusher roll indexing means.

15. In a thread grinding machine, a base having a horizontal carriage mounted for reciprocal travel thereon, a cross slide mounted for linear sliding movement on the carriage transversely to said reciprocal travel, a support mounted on the cross slide for movement toward and away from the base, a grinding wheel rotatably mounted on the support, means on the base for rotating a workpiece in engagement with the bottom of the grinding wheel, means on the carriage for advancing the cross slide to bring the grinding wheel into operation against the top of the workpiece, a crusher roll, means on the carriage for automatically retracting the cross slide to bring the grinding wheel into cooperation with the top of the crusher roll after a predetermined number of thread grinding operations, a milling cutter rotatably mounted on the cross slide for rotation in the plane of rotation of the crusher roll, means on the cross slide for adjusting the vertical position of the milling cutter to position the bot- 10 tom of the milling cutter in alignment with the top of the workpiece, and manually controlled means on the carriage for advancing the cross slide to bring the milling cutter into operation against the top of the crusher roll.

16. In a thread grinding machine, a base, a carriage mounted for travel in opposite directions on the base, a cross slide mounted for linear sliding movement on the carriage transversely to the carriage travel, a support mounted on the cross slide for movement toward and away from the carriage, a grinding wheel rotatably mounted on the support, power means on the secondary slide for rotating the grinding wheel, means biasing the secondary slide toward the carriage, adjustable means on the cross slide for limiting downward movement of the support, means on the base for rotating a workpiece in cooperation with the bottom of the grinding wheel, means on the carriage for advancing the cross slide to bring the grinding wheel into operation against the top of the workpiece, a crusher roll, means for positioning the crusher roll in radial alignment with the grinding wheel for engagement with the bottom of the milling cutter, power means on the carriage for driving the crusher roll, means on the carriage for retracting the cross slide to bring the grinding wheel into engagement with the top of the crusher roll after a predetermined number of thread grinding operations, a milling cutter rotatably mounted on the cross slide for rotation in radial alignment with the grinding wheel, power means on the cross slide for driving the milling cutter, means on the cross slide for positioning the milling cutter with its bottom in alignment with the top of the workpiece, and manually controlled means on the carriage for advancing the cross slide to bring the milling cutter into engagement against the top of the crusher roll.

17. In a thread grinding machine, a base. a carriage mounted for travel in opposite directions, a cross slide mounted for linear sliding movement on the carriage transversely to the carriage travel, a support mounted on the cross slide for movement toward and away from the carriage, a grinding wheel rotatably mounted on the support, power means on the support for rotating the grinding wheel, means biasing the support toward the carriage, indexable stop means on the cross slide for limiting downward movement of the support, means on the base for rotating a workpiece, means on the carriage for advancing the cross slide to bring the grinding wheel into operation against the top of the workpiece, a crusher roll, indexable means on the carriage for positioning the crusher roll at varying elevations in radial alignment with the grinding wheel, power means on the carriage for driving the crusher roll, means on the carriage for retracting the cross slide to bring the grinding Wheel into cooperation with the crusher roll after a predetermined number of thread grinding operations, said last named means being effective for indexing the support stop means, a milling cutter rotatably mounted on the cross slide for rotation in the plane of rotation of the grinding wheel and crusher roll, power means on the cross slide for driving the milling cutter, means on the carriage for positioning the milling cutter with its bottom in substantial alignment with the top of the workpiece, and manually controlled means on the carriage for advancing the cross slide to bring the milling cutter into operation against the crusher roll and for indexing the crusher roll positioning means.

18. In a thread grinding machine, a base having a horizontal carriage thereon mounted for reciprocal travel, a cross slide mounted for linear sliding movement on the carriage transversely to said reciprocal travel, a secondary slide mounted on the main slide for vertical sliding movement at right angles to the path of movement of the cross slide, a grinding wheel rotatably mounted on the secondary slide, power means on the secondary slide for rotating the grinding wheel, fluid pressure actuated means biasing the secondary slide toward the carriage, indexable stop means on the cross slide for limiting the downward movement of the secondary slide, means on the base for rotating a workpiece, means on the carriage for advancing the cross slide to bring the grinding wheel into operation against the top of the workpiece, a crusher roll, indexable means on the carriage for positioning the crusher roll on varying elevations in the plane of rotation of the grinding wheel, means on the carriage for periodically retracting the cross slide to bring the grinding wheel into cooperation with the crusher roll after a predetermined number of thread grinding operations, said last named means being arranged to index the secondary slide positioning means, a milling cutter rotatably mounted on the cross slide for rotation in radial alignment with the grinding wheel and crusher roll, vertically movable means on the cross slide for positioning the milling cutter with its bottom in substantial alignment with the top of the workpiece, and manually controlled means on the carriage for advancing the cross slide to bring the milling cutter into operation against the crusher roll and for indexing the crusher roll positioning means.

19. In a thread grinding machine, a base having a horizontal carriage thereon mounted for reciprocal travel, a cross slide mounted for linear sliding movement on the carriage transversely to said reciprocal travel, a secondary slide mounted on the cross slide for vertical sliding movement at right angles to the path of movement of the cross slide, a grinding wheel rotatably mounted on the secondary slide, power means for rotating the grinding wheel, fluid pressure actuated means biasing the secondary slide toward the carriage, means carried by the cross slide for positioning the secondary slide including a lost motion connection permitting limited free movement of the secondary slide, means associated with said cross slide including a ratchet for indexing the last named means toward the carriage, means on the base for rotating a workpiece, means on the carriage for advancing the cross slide to bring the grinding wheel into operation against the workpiece, a crusher roll, indexable means associated with the carriage including a ratchet for positioning the crusher roll at varying elevations in radial alignment with the grinding wheel, means connected to the crusher roll including a clutch for driving said crusher roll, means including a counter for automatically retracting the cross slide to bring the grinding wheel into cooperation with the crusher roll after a predetermined number of thread grinding operations, said last named means being arranged to actuate the secondary slide indexing means, a milling cutter rotatably mounted on the cross slide for rotation in the plane of rotation of the grinding wheel and crusher roll, power means on the cross slide for driving the milling cutter, means on the cross slide for adjusting the vertical position of the milling cutter, and manually controlled means on the carriage for advancing the cross slide to bring the milling cutter into operation against the crusher roll and for indexing the crusher roll positioning means.

20. In a thread grinding machine, a base having a horizontal carriage thereon, a cross slide mounted for linear sliding movement on the carriage, a secondary slide mounted on the main slide for vertical sliding movement at right angles to the path of movement of the cross slide, a grinding Wheel rotatably mounted on the secondary slide, power means on the secondary slide for rotating the grinding wheel, fluid pressure actuated means biasing the secondary slide toward the carriage, means on the cross slide for positioning the secondary slide including a lost motion connection permitting limited free movement of the secondary slide, means associated with the cross slide including a ratchet for indexing the last named means toward the carriage, means on the base for rotating a workpiece, means on the carriage for advancing the cross slide to bring the grinding wheel into operation against the top of the workpiece, a crusher roll, indexable means associated with the carriage including a ratchet for positioning the crusher roll at varying elevations in radial alignment with the grinding wheel, means connected to the crusher roll including a clutch for driving said crusher roll, means associated with the carriage including a counter for automatically retracting the cross slide to bring the grinding wheel into engagement with the top of the crusher roll after a predetermined number of thread grinding operations, said last named means being arranged to actuate the secondary slide indexing means, a milling cutter rotatably mounted on the cross slide for rotation in the plane of rotation of the grinding wheel and crusher roll, power means on the cross slide for driving the milling cutter, vertically movable means on the cross slide for positioning the milling cutter with its bottom in substantial alignment with the top of the workpiece, and manually controlled means on the carriage for advancing the cross slide to bring the milling cutter into operation against the crusher roll and for indexing the crusher roll positioning means.

References Cited in the file of this patent UNITED STATES PATENTS 1,023,389 Olsen Apr. 16, 1912 2,585,990 Baldenhofer Feb. 19, 1952 2,586,235 Krafit Feb. 19, 1952 

